Apple may block push notifications for unlocked iPhones

A Czech-based developer has found that Apple's push notification servers …

A company called PoweryBase recently noticed that some users were having problems with its NotifyMe app, which allows uses to set reminders that are pushed to an iPhone at a specified time. It was able to trace the problem to users that had unlocked their iPhones to work on a different mobile carrier, which may actually be by design on Apple's part.

The problem stems from how the push notification service works with Apple's servers. An application that uses push notifications will attempt to register with APNS on launch. The APNS will respond with a unique token that allows notifications to be routed to a specific phone. However, APNS simply does not respond to a registration request from a phone with an unauthorized unlock hack. If an application isn't coded to time out after a certain period of waiting for the APNS request, it will essentially appear to be locked up, waiting for a response that will never come.

PoweryBase notes that not responding to a request is common for some smaller network services, but that typically a service like Apple's Push Notifications would return an error that applications could then handle appropriately. Apple may have either not tested what would happen with a hacked iPhone or may have simply intended for APNS to not respond to requests from "unauthorized" devices.

It's possible developers can update their apps to take the issue into account—that's what PoweryBase intends to do—but I wouldn't hold your breath waiting for Apple to change how the server works just for unlocked phones. Essentially, users of unlocked phones should avoid apps that rely mainly on push notifications or turn the feature off for other apps.